Remove log cleanup cronjob from review

Gerrit should be cleaning up logfiles on its own now. That means we
don't need a cronjob to do it. This is step 1 of a two step process
where we first have ansible remove the cronjob then step 2 will remove
the cronjob from ansible entirely.

Change-Id: I82825de65c28cea43e9a472884b880d6f01efabe

playbooks/roles/gerrit/tasks/main.yaml

@@ -347,14 +347,12 @@
     minute: 17
     hour: 4
 
-# Gerrit rotates their own logs, but doesn't clean them out
-# Delete logs older than a month
-# TODO set state to absent then remove entirely after we upgrade to
-# Gerrit 3.10 and set log.timeToKeep to do this rotation natively.
+# Gerrit rotates logs on its own now. Clean up our old cron job that did it
+# before.
 - name: Set up cron job to clean old gerrit logs
   cron:
     name: clear-gerrit-logs
-    state: present
+    state: absent
     user: gerrit2
     job: 'find /home/gerrit2/review_site/logs/*.gz -mtime +30 -exec rm -f {} \;'
     minute: 1